can someone explain to me how to figure out percentiles?
this is the question:
given 100, 90, 80, 75, 70, 60, 30, 25, 5, 4, what score corresponds to the 70th percentile?
please help ! thanks !
this is the question:
given 100, 90, 80, 75, 70, 60, 30, 25, 5, 4, what score corresponds to the 70th percentile?
please help ! thanks !
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First, you need to know that there are several definitions of percentile. But the simplest 2 definitions (using your data and question) are
1) after ranking your data from lowest to highest, the lowest data point below which 70% lie. In this case the 70th percentile is 80 (the 8th point), because 7/10 (70%) lie below that.
2) after ranking your data from lowest to highest, the lowest data point with 70% equal or below (or if a tie-breaker is needed, eg if there were 11 data points, the score below which 70% lie, which is the above definition). In this case, there is a 70th percentile point, ie the 7th point, 75.
Other definitions involve taking some sort of average of more than one data point and there are several ways of doing that!
If you have not been given a definition, I'd go with the 2nd one, 75, which is the lowest value including the first 70%. Because no tie-breaker is needed and there are no other data points of 75, this means that 30% are above this point. So this definition is simple and with most data gives a good chance of having 70% equal to or below the 70th percentile and 30% above.
1) after ranking your data from lowest to highest, the lowest data point below which 70% lie. In this case the 70th percentile is 80 (the 8th point), because 7/10 (70%) lie below that.
2) after ranking your data from lowest to highest, the lowest data point with 70% equal or below (or if a tie-breaker is needed, eg if there were 11 data points, the score below which 70% lie, which is the above definition). In this case, there is a 70th percentile point, ie the 7th point, 75.
Other definitions involve taking some sort of average of more than one data point and there are several ways of doing that!
If you have not been given a definition, I'd go with the 2nd one, 75, which is the lowest value including the first 70%. Because no tie-breaker is needed and there are no other data points of 75, this means that 30% are above this point. So this definition is simple and with most data gives a good chance of having 70% equal to or below the 70th percentile and 30% above.
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It's out of 100, so 70% of 100 is....70.
70th percentile is 70.
70th percentile is 70.